This application claims the priority of German Patent Application, Serial No. 102 02 804.4, filed Jan. 25, 2002 pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference.
The present invention relates to an arrangement for displacement of a current collector relative to a trolley wire and in particular an arrangement for displacement of a current collector, which is a component of a track-bound transport vehicle.
A current collector, which is part of a track-bound vehicle used in local traffic, such as for example a trolley or street car, is normally urged against the trolley wire by means of mechanical springs. The spring action permits varying lifting positions of the current collector between the trolley wire and the support at the roof of the vehicle to be adjusted during travel by the track-bound vehicle along a route.
It is generally known that for local traffic, lowering the current collector away from the trolley wire is carried out through an electrical drive. The drive can be a compact drive or a linear drive including a spindle.
Furthermore, it is known in the prior art to provide the current collector with a device by which a rapid-action lowering of the current collector can be realized when such lowering motion is forced by problems of various types, to thereby prevent damage to the current collector and the trolley wire.
Such rapid-action lowering devices suffer however from various drawbacks independent of their construction or configuration. In particular, when the current collector was lowered, for example due to an error, the current collector can then not be reactivated instantaneously. As a result, the transport vehicle may have to be towed. In some cases the transport vehicle has to be towed by means of an emergency towing vehicle. Oftentimes, passengers travelling in the vehicle are then required to leave the vehicle. Especially along the driving route of such a vehicle, the requirement of evacuating of the passengers from the transport vehicle creates unfavorable conditions especially for older or disabled passengers so that such an event may cause considerable discomfort and problems.
In view of the afore-described shortcomings, it would therefore be desirable and advantageous to provide an improved arrangement for a displacement of a current collector relative to the trolley wire, which obviates prior art shortcomings.
According to one aspect of the present invention, an arrangement for moving a current collector of a track-bound transport vehicle relative to a trolley wire includes an electric drive having an actuating member for linkage to a pivot shaft of a current collector which is urged by spring force against a trolley wire; a rapid-action-action lowering unit integrated in the actuating member and including a energy storage reservoir under pressure; and a sensor operatively connected to the current collector and coupling the energy storage reservoir with the electric drive.
The present invention resolves prior art problems by ensuring not only a rapid-action lowering of the current collector when required but that the current collector can be immediately reactivated, for example when an unwanted lowering of the current collector has occurred.
According to one feature of the present invention the rapid-action lowering unit provided with a energy storage reservoir under pressure is integrated into the actuating member between the electric drive and the pivoting shaft of the current collector and can be activated by means of mechanical, electrical hydraulic or pneumatic energy. The energy storage reservoir is coupled to a sensor associated with the current collector, in particular in the area where a rocker is located. When an irregularity is detected by the sensor in the area of the rocker, the rapid-action lowering unit becomes activated without noticeable delay for an immediate separation of the current collector from the trolley wire. As a result, the force of the lifting spring urging the current collector against the trolley wire is thereby overcome and at the same time the electrical drive can be shut down temporarily, at least for the first moment of lowering. After separation of the current collector from the trolley wire, the electric drive can then again be switched on taking up the lowering of the current collector with the rapid-action lowering unit or alternatively it can remain inactive for the duration of lowering the current collector.
Furthermore, the rapid-action lowering unit ensures that the free-running between the electrical drive and the pivoting shaft of the current collector is bridged in order to reduce friction and to ensure that a separation of the current collector from the trolley wire is realized without delay.
In the event, the current collector was inadvertently lowered due to erroneous information, the current collector can again be pressed against the trolley wire due to a stiffening of the rapid-action lowering unit, which is integrated into the control mechanism thereby ensuring that by means of the electric drive, or optionally in conjunction with the lifting springs, the current collector can again be pressed against the trolley wire, with the result that the transport vehicle can at least move, even if slowly, by itself.
The energy storage reservoir associated with the rapid-action lowering unit is preferably configured so it can be reactivated without complex technical operation.
In an especially advantageous embodiment of the present invention, the rapid-action lowering unit includes a pneumatically operated piston-cylinder assembly connected to a pneumatic pressure tank. Preferably, the pneumatic pressure tank can be configured also as a commercially available CO2-container (pressure gas cartridge), which is easily exchangeable.
According to another feature of the present invention, the cylinder of the piston-cylinder assembly is connected to the pivoting shaft of the current collector by means of a spindle of an electric linear drive, and the piston rod is connected to the pivoting shaft of the current collector by means of the Y-shaped rocking lever.
Normally, the rocking lever carries out the de-coupling of the electrical drive from the pivoting shaft to be free-running at a range to be desired. As a result, the electrical drive cannot impact the movements of the current collector through higher frictional drag.
In accordance with another feature of the present invention, it is ensured that the influx of pressure gas into the piston compartment of the cylinder of the piston-cylinder assembly by means of the throttle opening can dissipate unobstructedly into the surrounding area. The return spring, which is incorporated into the piston rod compartment ensures that the piston cylinder assembly in itself is stiffening to thereby cause a direct impact from the electrical drive onto the pivoting shaft of the current collector.
In accordance with a further feature of the present invention, the coordination of the sequence of movements after a rapid-action lowering was triggered, a control that is memory programmable is incorporated in the sensor and the energy storage reservoir on the one hand and the electrical drive on the other hand.